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J J LiPuma

Publications and source records attributed to J J LiPuma.

At least 37 records · Page 2Linked to original sources
PubMed1998

Burkholderia cepacia. Management issues and new insights.

Although Burkholderia cepacia colonizes a relatively small proportion of individuals with cystic fibrosis (CF), it is associated with significant morbidity and mortality, and has had a profound impact on infection control practices. This article reviews the current understanding of the epidemiology of B. cepacia infection, describes important recent developments in the microbiology and taxonomy of this species, and presents issues that remain obstacles to defining the optimal management of B. cepacia infection in CF.

Burkholderia Infections↗
PubMed1998

Burkholderia cepacia epidemiology and pathogenesis: implications for infection control.

Much has been learned during the past 2 years about the microbiology and taxonomy of Burkholderia cepacia. Several distinct species have been identified in what is now referred to as the B. cepacia complex. Preliminary studies indicate that certain of these species are more likely to colonize and cause severe pulmonary infection in persons with cystic fibrosis. Ongoing investigations will expand these findings and have the potential to modify current infection control policies. The commercial use of B. cepacia as an antifungal biopesticide and in bioremediation has attracted increasing attention from industry recently and raises concerns within the cystic fibrosis community. Consensus regarding the potential threat of such uses to cystic fibrosis patients is being sought by governmental agencies and agricultural and biomedical researchers.

Anti-Bacterial Agents↗
PubMed1997

Cloning and characterization of the haemocin immunity gene of Haemophilus influenzae.

The bacteriocin haemocin is produced by most type b strains of Haemophilus influenzae, including strains of diverse genetic lineage, and is toxic to virtually all nontypeable H. influenzae strains. An H. influenzae transformant bearing a plasmid with a 1.5-kbp chromosomal fragment capable of conferring haemocin immunity on a haemocin-susceptible H. influenzae mutant was selected by using partially purified haemocin. Deletional and site-directed mutagenesis localized the haemocin immunity gene to the 3' open reading frame (ORF) within this chromosomal fragment. Subcloning of this ORF demonstrated that it was sufficient to confer haemocin immunity on wild-type haemocin-susceptible H. influenzae strains as well as haemocin-susceptible strains of Escherichia coli. This ORF, designated hmcl, encodes a 105-amino-acid protein with an estimated molecular mass of 12.6 kDa. Primer extension analysis revealed a putative transcriptional start site 34 bp upstream of the start codon, and the presence of a promoter immediately upstream of hmcI was confirmed by cloning the gene into a promoterless chloramphenicol acetyltransferase vector. To characterize the hmcI gene product, a His-HmcI fusion protein was constructed.

Amino Acid Sequence↗
PubMed1997

Identification of Burkholderia cepacia isolates from patients with cystic fibrosis and use of a simple new selective medium.

We evaluated 819 isolates referred to us as "Burkholderia cepacia" from cystic fibrosis (CF) clinics and research laboratories from five countries; 28 (3.4%) were not B. cepacia. A further 12 (1.5%) organisms appeared to be other Burkholderia species, but identification could not be confirmed by conventional means. The most prevalently misidentified organisms were Stenotrophomonas maltophilia, Alcaligenes xylosoxidans, and Comamonas acidovorans. Many of these organisms grew on oxidation-fermentation polymyxin-bacitracin-lactose (OFPBL) and Pseudomonas cepacia agars, selective media currently used for B. cepacia isolation. We developed a new medium, B. cepacia selective agar (BCSA), which is more enriched for the growth of B. cepacia yet which is more selective against other organisms than currently available selective agars. A total of 190 of 191 (99.5%) isolates of B. cepacia from patients with CF grew on BCSA without vancomycin, whereas 100% grew on OFPBL agar and 179 (94.2%) grew on P. cepacia agar. Of 189 other gram-negative and gram-positive organisms tested, 10 (5.3%) grew on BCSA without vancomycin. The addition of vancomycin to BCSA lowered the false positivity rate to 3.7% without further inhibition of B. cepacia. The false positivity rates for OFPBL and P. cepacia agars were 19.6 and 13.8%, respectively. Isolates of B. cepacia from CF patients grew most quickly on BCSA, with 201 of 205 (98.0%) being readily visible within 24 h, whereas 182 (88.8%) grew on OFPBL agar and 162 (79.0%) grew on P. cepacia agar within 24 h. We propose that the use of BCSA will allow investigators to overcome many of the difficulties associated with the identification of B. cepacia and should be considered for use as a primary isolation agar for specimens from patients with CF.

Bacterial Typing Techniques↗
PubMed1996

Survival of Burkholderia cepacia on environmental surfaces.

Burkholderia (Pseudomonas) cepacia is an important pathogen amongst persons with cystic fibrosis (CF), and evidence suggests that transmission of strains within CF clinics contributes to pulmonary colonization of some patients. In order to optimize preventive strategies, the survival of B. cepacia on various environmental surfaces, including cotton cloth, stainless steel, latex and polyvinylchloride (PVC) tubing, was investigated. For surface inoculation, bacteria were suspended in phosphate buffered saline, sputum from CF patients, or sputum from persons without CF. The results demonstrate that amongst the strains examined, organisms survived significantly (P < 0.001) longer when suspended in sputum from CF patients than in either non-CF sputum or buffered saline. Significant (P < 0.001) differences in survival on the various surfaces were found; survival was greatest on PVC. Significant (P < 0.001) strain-to-strain differences in survival were also demonstrated; patient isolates representing predominant CF centre ribotypes survived longest. These data demonstrate that (1) B. cepacia can survive for long periods in respiratory droplets on environmental surfaces typically found in CF clinics, (2) undefined factors in sputum from patients with CF may contribute to survival of B. cepacia, and (3) strain-to-strain variation in survival time may affect strain transmissibility.

Analysis of Variance↗
PubMed1996

Nontypeable Haemophilus influenzae susceptibility: effect of inoculum size and beta-lactamase production.

The activities of cefixime, cefpodoxime, cefprozil, cefuroxime, loracarbef, and amoxicillin/clavulanate against 72 clinical isolates of nontypeable Haemophilus influenzae were determined by using an agar dilution method. The effects of beta-lactamase production and bacterial inoculum size were investigated. All antimicrobials exhibited a significant inoculum effect, demonstrating the importance of accurately determining inoculum size in the performance of antimicrobial susceptibility testing of H. influenzae.

Anti-Bacterial Agents↗
PubMed1995

Recovery of Pseudomonas cepacia and other Pseudomonas species from the environment.

Nine hundred sixteen cultures were obtained from homes of patients with cystic fibrosis, control homes, salad bars, and food markets, and analyzed for the presence of Pseudomonas cepacia and related bacteria. P cepacia was recovered from 5 (18%) of 27 homes, and from 20 (4%) of 509 cultures collected outside of homes. Relative to other pseudomonads, P cepacia is found infrequently in the environment. It is not clear how frequently these sources contribute to acquisition of this bacteria by persons with cystic fibrosis.

Bacteriological Techniques↗
PubMed1995

A universal approach to bacterial molecular epidemiology by polymerase chain reaction ribotyping.

Oligonucleotide primers complementary to conserved regions of the 16S and 23S ribosomal RNA genes were used to amplify the 16S-23S intergenic spacer region of bacterial pathogens. The amplification patterns produced were compared for their potential use in molecular epidemiologic analysis. This method, polymerase chain reaction (PCR) ribotyping, was applied to isolates of Staphylococcus aureus, Enterococcus faecium, Escherichia coli, and Enterobacter species. Length polymorphisms in the amplified DNA distinguished unrelated strains of all bacteria. The banding patterns of 3 S. aureus isolates from the blood of 1 patient on 3 consecutive days were identical. Plasmid analysis, biotyping, and antibiograms were also obtained on the Enterobacter isolates. All three of these methods showed considerable variability after in vitro passage of bacteria, but PCR ribotypes remained stable. Results demonstrate the utility of the conserved primers for PCR ribotyping, a widely applicable method for the molecular epidemiology of genetically diverse bacteria.

Bacterial Typing Techniques↗
PubMed1995

Antibacterial agents in pediatrics.

The utility of various antibacterial agents for therapy of infectious diseases in children is determined by the unique pharmacokinetics and potential toxicity in children. The important age-related principle of pharmacokinetics is reviewed in the first section of this article; the second section focuses on specific therapeutic agents and their use in children. Particular emphasis is given to the use of new antibiotics in children, including the new oral cephalosporins and macrolides.

Adolescent↗
PubMed1994

Characterization of PCR-ribotyping for Burkholderia (Pseudomonas) cepacia.

Ribotyping, a method of genotyping bacterial isolates for epidemiologic study, uses rRNA as a probe to detect chromosomal restriction fragment length polymorphisms. Although ribotyping is accurate, its utility is limited by the labor and time necessary for Southern blot analysis. PCR-ribotyping uses PCR to amplify the 16S-23S intergenic spacer region of the bacterial rRNA operon. Length heterogeneity in the spacer region has previously been found to be useful as an alternative to standard ribotyping in a study of Burkholderia (Pseudomonas) cepacia. To further analyze the accuracy of PCR-ribotyping, three groups of previously characterized isolates of B. cepacia were investigated. PCR-ribotyping grouped 90 isolates recovered from seven well-defined epidemics into the correct outbreak group with a mean concordance of 93%. Both standard ribotyping and PCR-ribotyping separated 15 unrelated isolates into 14 types. In an analysis of 83 B. cepacia isolates from chronically colonized cystic fibrosis patients, the concordance of PCR-ribotyping with standard ribotyping ranged from 83 to 100%, with a mean of 98%. One isolate from a chronically colonized patient had a different type by standard ribotyping but was identical to the other isolates from this patient by PCR-ribotyping. Thus, PCR-ribotyping is a rapid and accurate method for typing B. cepacia and is less labor intensive than standard ribotyping.

Base Sequence↗
PubMed1993

Source of Pseudomonas cepacia: ribotyping of isolates from patients and from the environment.

Ribotyping, an analysis of bacterial strain identity based on chromosomal restriction fragment length polymorphisms, was performed on 68 isolates of Pseudomonas cepacia recovered from patients receiving care at the two children's hospitals in Philadelphia and from environmental samples. Twenty different ribotypes were identified. Ribotype R3 predominated among isolates from all three sources. These findings are consistent with the acquisition of P. cepacia from the environment or by person-to-person transmission.

Burkholderia cepacia↗
PubMed1992

Molecular epidemiology of Pseudomonas cepacia determined by polymerase chain reaction ribotyping.

Traditional ribotyping detects genomic restriction fragment length polymorphisms by probing chromosomal DNA with rRNA. Although it is a powerful method for determining the molecular epidemiology of bacterial pathogens, technical difficulties limit its application. As an alternative, polymorphisms were sought in the 16S-23S spacer regions of bacterial rRNA genes by use of the polymerase chain reaction (PCR). Chromosomal DNA from isolates of Pseudomonas cepacia was used as a template in the PCR with oligonucleotide primers complementary to highly conserved sequences flanking the spacer regions of the rRNA genes. Length polymorphisms in the amplified DNA distinguished unrelated isolates of P. cepacia. Isolates of P. cepacia previously implicated in person-to-person transmission were shown to have identical amplification patterns. These data demonstrate the utility of this new PCR ribotyping method for determining the molecular epidemiology of bacterial species.

Bacterial Typing Techniques↗
PubMed1991

Epidemiology and natural history of urinary tract infections in children.

Recent retrospective surveys have supported previous investigations in demonstrating the incidence of UTI during infancy; 0.3% to 1.2% of infants develop symptomatic UTI during the first year of life. Boys are more commonly infected during the first 3 months of life. After the first year, symptomatic UTI is much more frequent among girls. Similarly, asymptomatic bacteriuria is more frequently detected in boys than in girls during the first 12 months of life. Thereafter, the incidence decreases markedly in boys but increases in girls. Recent investigations indicate that lack of circumcision is a risk factor for UTI among male infants. Recurrent UTI is common and frequently asymptomatic. The most important microbiologic factor that is associated with E. coli causing acute pyelonephritis is adherence mediated by P fimbriae. Other factors, such as capsule, lipopolysaccharide, aerobactin production, and serum resistance, also determine the invasiveness of E. coli. Vesicoureteral reflux appears to be an important host factor predisposing to UTI. Microbiologic and host factors that are determinants of renal scarring are under investigation.

Bacterial Infections↗
PubMed1991

Ribotype stability of serial pulmonary isolates of Pseudomonas cepacia.

Eighty-three isolates of Pseudomonas capacia were recovered from respiratory secretions from 12 chronically colonized cystic fibrosis patients and examined by ribotype analysis. In 9 patients, the ribotype of the cultured P. cepacia remained unchanged throughout the entire period of observation, indicating chronic pulmonary colonization with a single strain. In each of the remaining 3 patients, two genetically distinct strains were detected among serial P. cepacia isolates. No significant change in clinical condition was correlated with the change in identity of the colonizing strain. In control experiments, the stability of strain ribotype was demonstrated among isolated that had been subcultured 100 times in vitro and among isolates recovered from chronically colonized mice. These data demonstrate the utility of ribotype analysis and indicate that most chronically colonized cystic fibrosis patients harbor a single strain of P. cepacia for prolonged periods.

Animals↗